Telephone-exchange system.



N0. 632,066. Patented Aug. 29, 899.

' C. E. SCRIBNER.

TELEPHONE EXCHANGE SYSTEM.

(Application filed Dec. 18, 1888.)

3 Sheets-Sheet I.

(No Model.)

6 IIIIIIIIII P. p

No. 632,066. Patented Aug. 29, I899.

C. E. SDBIBNER.

TELEPHONE EXCHANGE SYSTEM.

(Application filed Dec. 18, 1888.) (No Model.) 3 Sheets-Sheet 2;

llllllllll ll-lllll ll-llmlllll lllllll! -|II-l|ll Patented Aug. 29, I399. C. E. SGRIBNER.

TELEPHONE EXCHANGE SYSTEM.

(Application filed Dec. 18, 1888.) (No Model.)

3 Sheets-Sheet 3,

us ca. Hum-ammo, WASHINGTON. o. c.

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE \VESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 632,066, dated August 29, 1899. Application filed December 18,1888. Serial Np. 294,004. (No model.)

To all whom, it may concern: annunciator, the battery-circuit connected Be it known that LCHARLES E. SCRIBNER, through said coils,and a branch from bet-ween' a citizen of the United States, residing at Chisaid coils to a pair of cords or other connectcago, in the county of Cook and State of Illiing device, the different windings of the an- 5 nois, have invented a certain new and useful nunciatorbeing of a differentnumber of turns Improvement in Telephone-Exchange Sysand so apportioned that when two lines are terns, (Case No. 185,) of which the following connected by the cord the currents through is a full, clear, concise, and exact descripthe different windings will be such as to praction, reference beinghad to the accompanying tically neutralize the core. 1o drawings, forming a part of this specification. By the use of my invention the spring-jack Myinventionrelatesto telephone-exchange switches heretofore generally used may be systems, certain featuresthereof being adaptdispensed with, simple metallic sockets being ed for use in exchanges having only one used instead. Moreover,no special test-wires switchboard, while all the features thereof are required in multiple systems. 15 may be advantageously employed in ex- My invention is illustrated in the acconv changes having multiple switchboards. panying drawings, in which I will describe my invention more espe- Figure 1 isaview illustrative of three telecially as applied in multiple systems,referring phone-lines, each connected with three multionly incidentally to its application to singleple switchboards, each line extending from 20 board exchanges. its socket on the last board to a polarized an- My invention consists, first, in the use of nunciator and thence to ground, the operapolarized individual annunciators in the teletors apparatus being shown at the first and phone-lines, in combination with a battery last boards. Fig. 2 is a detailed view showconnected with the connecting devices and so ing the manner of winding the clearing-out 25 arranged that when any two lines are conannunciator differentially. Fig. 3 is a view nected together the battery-current will be of a subscribers outfit, a single-stroke bell closed through the polarized individual anbeing shown as a signal-receiver, the magnunciators in a direction to prevent their being neto-generatorbeing of the usual type adapted operated; second, in extending each line from to send current in reversals. Fig. 4: is a dia- 30 its switch or plug socket on the last board gram showingasingle switchboard with three through a polarized individual annunciator lines connected therewith and two of said and thence to ground, the annunciators being lines being connected together, the clearingof high resistance and provided with a large out annunciators being omitted from the pairs number of turns to act as self-induction coils of connecting-cords, as is sometimes desir- 3 5 when two lines are connected together; third, able-as, for example, upon toll-lines.

in providing connecting, signaling, answer- Like parts are indicated by similar letters ing, and testing apparatus at each of the and figures of reference throughoutthe differboards so arranged that communication may cut figures. be had between the central oiiiee and the dif- Referring now to Fig. 1, line a after con- 0 o ferent subscribers stations, as desired, to ennecting with the sockets 1), b and b on the able one subscriber to be put in communicadifierent boards passes through theindividual tion with any other idle subscriber; fourth, in polarized annunciator con board 1 and thence aspecial battery-circuitin connection with the to ground. Line (Z is connected in like manconnecting devices, whereby theindividual nor with sockets e e 6 and from the socket 5 5 polarized annunciators of two connected lines e through an individual polarized annunciare prevented from being thrown down while ator on board 2 and thence to ground. Line connected for conversation, the presence of g coming from its subscribers station (for the battery-current on any lines thus condetail see Fig. 3) is connected with its sockets nected atone board affording means for testh h 7L3 and thence through polarized annun- 50 ing the lines at any other of the boards, and, ciator i on board 3 and to ground. The lines fifth, in a diiferentially wound clearing-out ct and (Z are shown connected for conversation at board 1 between sockets b and 6, while the annunciator of line g at board 3 is shown down, as if a call had just been sent in, while the test-plug at board 3 is shown applied to socket e as in the act of testing line 01. Referring now to board 1 of Fig. 1, it will be seen that theplugs 7010' are connected by the cords k a usual calling-key being included in each of the cords. The clearingout annunciator Z is Wound differentially and the circuit through the coils thereof may be traced from ground through battery m and thence through winding n in one direction and thence back through winding 0, having the greater number of turns in the opposite direction, and thence to ground. The strand of the cords k k is connected through Wire m with a point between the differential coils n 0, as shown. The battery m is of such strength and its polarity such that the individual annunciators of any two connected lines, as annunciators c and f, will be retained in position as long as the connection between the lines remains. The current of battery m is effective in looking the annunciators c fin position,while at the same time, being present at sockets b b and e 6 serves, when the proper test is applied, to indicate that the lines are in use. The adjustment of the bell of each subscribers outfit shouldbe such that there would be no danger of calling a subseriber simply by the current from battery m. A special calling-battery p is provided, which should be of sufficient strength to operate any subscribers signal-receiving device or single-stroke bell when closed to his line. The different coils n 0 of the clearing-out annunciator are not of the same number of turns, the coil 0 having the greater number. The resistance of the individual annunciators is such that the current derived through coil 0 will have practically the same efiect upon the core as the greater current through the less number of turns in the coil 02. Hence in effect the clearing-out annunciator will be neutral so far as it is affected by current from battery m. It is evident that current from the magneto of either of two connected sub scribers will operate the clearing-out signal. Since the individual annunciators are never disconnected from their telephone-lines, respectively, they should be of high resistance and preferably of many turns, so as to act as self-induction coils, for reasons well understood. Thus, as shown in Fig. 4, the annunciator may be provided with a long core and wound with, say, ten thousand turns, and its resistance may he, say, five hundred ohms. The resistance of the polarized annunciators being known, the required amount of difference in the differential windingsn and 0 may be readily determined. As shown in Fig. 4, the lines q g are connected together by the pair of cords g ferent pairs arranged to make connection, with this battery. The individual annunciators q T, 850., of the diiferent lines are each wound with a large number of turns of fine wire, so that the self-induction of these individual annunciators will be sufficient to prevent any injurious effects upon the lines when connected together for conversation, although the individual annunciators remain connected therewith in ground branches, as shown. Thus simple sockets maybe used as switches upon the switchboard for the telephone-lines and the individual annunciators of any two lines, when the lines are connected together between their switches or connecting -pieces upon the switchboard will be shunted.

The operation of my system as applied to multiple switchboards is briefly as follows: Suppose a call sent over line a, throwing down shutter c at board 1. Operator at board 1 at once inserts plug is in socket b and brings her telephone into circuit, thus putting herself in communication with the subscriber of line a to receive the order, which we will say is for line d. Line dis then tested by applying test-plug p to socket e, and no current being indicated is evidence that the line is The plug it is then inserted, as shown,

idle. and the key in cord 70 is closed to the callingbattery, thus sending current over line d to indicate to the subscriber thereon that he is wanted. The two subscribers are thus placed in communication,their an no nciators remainin g in ground branches, as shown. nunciators being, however, of high resistance and provided with a large number of turns the ground connections will not to any injurious extent interfere with the circuit, and as the annunciators are held up by battery m no false signals will be made. The manner in which this prevention of false signals is accomplished may be described as follows: Current fiows'from battery m through one winding of the clearing-out annunciator Z to the cordcircuit 70 and thence to the plugs 70 7c. From these it finds circuit to the line-wires of the two lines with which the plugs are connected and thence to earth through their respective annunciators c and f. The polarity of battery m is so arranged with respect to the magnetic polarity of the individual annunciators that these shall not attracttheir armatures in a manner to release their shutters. If now a signaling current be sent from either substation as. a signal for disconnection, a large portion of the signal-current will find circuit through the clearing-out drop Z to earth, operating that drop. A part will pass through each of the individual annunciators to earth, but will fail to operate these, because they will be retained inoperative by the superior force of battery m. Either connected subscriber may clear out by hanging up his telephone and operating his generator. Suppose a call be sent over line g for line (Z. The operator testing at board 3,

These an- 7 as shown, will find current on the line and will thus know that the line is busy-that is, if the line were not in use the application of plug p to any socket would produce no response in the telephone of the operator testing, but if the line be in use a current will be shunted from the line by the grounded test-plug and passing through one helix of the induction-coil will induce a momentary current in the operators telephone. She will thus avoid crossing in upon connected lines.

The system herein described is of special advantage on account of its simplicity and cheapness. The problem of wiring large boards, which has been considered heretofore one of the most difficult, is made easy, since only half the number of connections are required by my system herein, the special test-circuits, one for each line, as hereinbefore used, being dispensed with; also, it will be observed that the spring-jack switches, which are very expensive owing to the superior workmanship and material required, are dispensed with.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The combination with two telephonelines each provided with a difierent connecting-piece on each of two or. more switchboards, and each permanently connected to ground through its individual polarized annunciator, of a connection between said lines at one of the boards and a battery closed in derived circuit through said annunciators to hold them in position to prevent false signals.

2. A pair of plugs connected together and to a grounded circuit between two unbalanced differential windings of an annunciator in said grounded circuit, a battery in said grounded circuit between the coil having the lesser number of turns, and circuits including resistance with which said plugs are adapted to be connected, the resistance of said circuits and the difference in the differential windings being apportioned to cause the current through the coils to have practically the same efiect upon each, and practically neutralize the annunciator-core.

3. In combination, two telephone-lines,connection sockets in branches from each line, a conductor uniting two sockets of the different lines, and an individual annunciator in a permanently-closed branch from each line of high resistance and self-induction, substantially as described.

4. The combination with two telephonelines connected together,of permanent ground branches, one from each line including a polarized annunciator, of a battery closed through said annunciators to retain them in position.

5. In combination, two telephone-lines, a conductor temporarily uniting the two lines, an individual annunciator for each line in a permanently-closed branch of the line of high resistance and self-induction, and means applied through the instrumentality of said conductor adapted to render said individual annunciators irresponsive to signaling-currents in the lines, substantially as described.

6. In combination, two telephone-lines, a socket connected with each line, a connecting-plug in each socket, a link conductor uniting the two plugs, an individual annunciator for each line in a permanently-closed branch from the line of high resistance and self induction, a clearingout annunciator connected with said link conductor, and means applied through the instrumentality of each of said plugs and sockets adapted to render the individual annunciators irresponsive to signaling-currents in the lines, substantially as described.

7. The combination with a telephone-line circuit, of an individual annunciator con nected in a permanentbranch circuitbetween the difierent sides thereof, said annunciator being arranged to be retained unresponsive to sign aling-currents through it by a continuous current through it, and a source of continuous current in a branch circuit between the difierent sides of the circuit; substantially as described.

8. The combination with a telephone-line circuit of an individual annunciator adapted to remain unresponsive to signaling-currents when a continuous current traverses its coils, connected in a permanent branch between the different sides of the said circuit, and a pair of connecting plugs and cords anda battery adapted to be connected between the difierent sides of the line-circuit when connection is made with said line, to prevent the subsequent operation of the individual an= nunciator; substantially as described.

9. The combination with a telephone-line of means for sending signaling-current over the same,said means being located at the sub station thereof, said line being provided with a permanently-closed branch of high impedance at the central office, a signal-receiving instrument located in said branch, a connection socket located in the line at the central office, a connecting-plug constituting a tem= porary terminal of another telephone-line adapted to be inserted in the said socket, and means applied through the instrumen tality of said connecting plug and socket adapted to render the said signal-receiving instrument irresponsive t0 currents sent from the subscribers station.

In witness whereof I hereunto subscribe my name this 1st day of December, A. D. 1888.

CHARLES E. SCRIBNER.

WVitnesses:

LESTER CLEMENT BARTON, CHAS. G. HAWLEY. 

